I already figured out that it's about sinking the result of assigning to
the SetHash. When you access it you get a proxy, that is the return
value of the lock-protected block, and the proxy gets sunk outside of
it, thus causing concurrent access to the SetHash.
On 14/11/17 16:03, Elizabeth Mattijsen wrote:
> reducing the code to:
>
> use nqp;
> my $lock = Lock.new;
> my $hash := nqp::hash;
> await ^16 .map: {
> start {
> for ^1000 {
> $lock.protect: { nqp::bindkey($hash,"a",1) }
> $lock.protect: { nqp::deletekey($hash,"a") }
> }
> }
> }
>
> does *not* make it crash. So it would appear that it’s not the lowlevel hash
> access that’s to blame. Looking at this with Telemetry.snapper, this *does*
> seem to eat a lot of memory very quickly. With a slightly bigger version,
> and much longer running, growth to about 490MB is observed (starting from
> 69MB) in 35 seconds, then remaining constant for about 125 seconds, after
> which a modest increase of only about 15KB per second was observed for the
> remainder of the run.
>
> So the next maybe it’s something in handling Proxy.
>
>
>> On 10 Nov 2017, at 03:28, David Lowe <j.david.l...@gmail.com> wrote:
>>
>> This crash still occurs with rakudo 2017.10.
>>
>> On Thu, Oct 5, 2017 at 9:10 PM, perl6 via RT <perl6-bugs-follo...@perl.org>
>> wrote:
>> Greetings,
>>
>> This message has been automatically generated in response to the
>> creation of a trouble ticket regarding:
>> "segmentation fault while concurrently updating SetHash",
>> a summary of which appears below.
>>
>> There is no need to reply to this message right now. Your ticket has been
>> assigned an ID of [perl #132225].
>>
>> Please include the string:
>>
>> [perl #132225]
>>
>> in the subject line of all future correspondence about this issue. To do so,
>> you may reply to this message.
>>
>> Thank you,
>> perl6-bugs-follo...@perl.org
>>
>> -------------------------------------------------------------------------
>> This short program crashes reliably (with a segmentation fault) on my
>> system:
>>
>> ```
>> #!/usr/bin/env perl6
>>
>> use v6.c;
>>
>> my $lock = Lock.new;
>> my $set = SetHash.new;
>> await (^12).map: {
>> start {
>> for (^1000) {
>> $lock.protect: { $set<1> = True }
>> $lock.protect: { $set<1> = False }
>> }
>> }
>> }
>> ```
>>
>> More information:
>>
>> ```
>> $ perl6 --version
>> This is Rakudo version 2017.09 built on MoarVM version 2017.09.1
>> implementing Perl 6.c.
>> ```
>>
>>
